This is a proposal to isolate and determine the structure and the mechanism of action of four membrane transport systems: the (Na ion plus K ion) dependent adenosine triphosphatase involved in cation pumping; the Ca ions ATPase of sarcoplasmic reticulum; the glucose transport system involved in facilitated diffusion of sugars, and the anion transport system in human erythrocyte membranes involved in exchange diffusion of anions. Finally, it is planned to characterize the erythrocyte membrane fibrous proteins involved in stabilization of the membrane, and the adenylate cyclase system involved in hormone interactions.